Conventional corner fittings allow for disposing door elements having different thicknesses, in particular glass door elements with different glass thicknesses on a center of rotation or an axis. The glass doors are for example double-action glass doors, which are disposed by means of the known corner fittings for example on a BTS-axis next to a sidepanel. Mostly, the structure of the prior art corner fittings comprises two fitting elements, which each include a locating portion for the door element, wherein an intermediate layer, which at least in sections, corresponds to the contour of the locating portions and is surrounded by the locating portion, is inserted between the locating portions and the door element. Outside the locating portions, the fitting elements form a free space within a cutout of the door element, which space is utilized for accommodating for example an axis between the fitting elements. With the intention to be able restrain door elements, in particular glass door elements, of different thicknesses between the fitting elements, the prior art corner fittings are dimensioned such that in their delivery condition, i.e. in an initial position, they are able to accommodate a door element having a predetermined glass thickness, for example with a glass thickness of 15 mm. In the event, another glass door element having a glass thickness of 10 mm were to be restrained in a corner fitting adjusted to a glass door element of 15 mm, in the prior art corner fitting, the intermediate layer is reinforced for compensating for the difference between the glass thicknesses. Therefore, in the present example, the intermediate layers are increased on both sides of the glass door element by 2.5 mm. In this case, by increasing the intermediate layers, the fitting elements abutting on both sides against the door element, move away from the door element by respectively 2.5 mm. Together with the fitting elements, also the cover or covering elements, which surround the fitting elements, move away from the door element on both sides by respectively 2.5 mm. Accordingly, a gap of 2.5 mm is automatically created on both sides of the door element, namely between the surfaces of the door element and the cover or covering element, which cover the fitting elements on both sides. To prevent said gap creation, the delivered cover or covering element, which is configured with the corner fitting adjusted to a glass thickness of a door element of 15 mm, would have to be exchanged against a cover or covering element which is deeper drawn for both sides of the door element. In an extreme case, namely with a corner fitting adapted to a glass door element of 15 mm thickness, which is intended to be converted for accommodating a glass door element of for example 7 mm thickness, the intermediate layers would have to compensate for the difference between 15 mm and 7 mm. This means, the intermediate layer on both sides of the door element needs to be increased by 4 mm. Thereby, the construction depth of the prior art corner fittings is larger by 4 mm on both sides of the door element. In addition, the clamping effect of the door element between the fitting elements and thereby the durability of the prior art corner fitting is reduced on account of the ever increasing intermediate layers.